Insulated Engineered Structural Member

ABSTRACT

An engineered structural member for use as, for example a stud, and a method for producing an engineered structural member, includes producing two flange members, preferably from nominal dimension solid lumber, providing slots in the flange members to receive opposite edges of a thin web, and assembling the edges of the web into the flange member slots to form an assemble engineered structural member. Preferably, an adhesive is used to bond the flange members to the web. An insulating material such as a rigid foam also may be arranged in the open spaces between the flange members at the exposed sides of the web to increase insulating capacity. The engineered structural member provides increased insulation capacity to a structure while reducing structure weight, improving strength and improving dimensional instability.

The present invention relates to the design and utilization of structures, in particular structural members used in building construction.

BACKGROUND OF THE INVENTION

Historically, the construction of structures such as walls and partitions in a building such as a house has been accomplished by assembling a frame having vertical members (“studs”) attached to horizontal header (aka, top plate) and footer members. Monolithic sawn wood of industry-standardized nominal dimensions frequently has been used for framing walls (for example, a nominal “2x4” piece of lumber has nominal dimensions of 1.5 inches by 3.5 inches, and a “2x6” piece of lumber has nominal dimensions of 1.5 inches by 5.5 inches). Typically the larger dimension has been arranged perpendicular to the planar surfaces of the wall. The surface of the wall facing inward toward the space defined by the wall typically is sheathed in a continuous sheet material, such as drywall or a paneling material, as is well known in the art.

Because the framing members are conventionally solid wood, the passage of utilities such as plumbing pipes, electrical conduits, network cabling, etc. has required substantial builder effort to drill passages through the relatively thick and dense wood of every vertical member of the wall in the case of utility runs parallel to the floor, and through often double-thickness header and footer members in the case of utility runs between floors. The tooling and labor required to create these multiple apertures in the vertical and horizontal directions substantially increases costs and slows construction.

The conventional approach to building such walls also has the disadvantage of creating thermal “bridging” paths between one side of the wall and the opposite side. Wood structural members typically have relatively poor insulation values. As a result the locations on the surface of the wall directly in front of the vertical studs and the header and footer are pathways for heat transfer, effectively bypassing any inter-wall insulation placed inside the wall between the studs. These localized areas can significantly reduce the effective insulation value of the entire wall. For example, in a situation where the wall is intended to provide insulation between a warm living space and a colder outside environment, “cold spots” or “cold corners” may be discerned where the wood framing members allow passage of heat from the inside to the outside environment and is a drain on natural resources.

Another disadvantage of the conventional solid-wood framing approach is that it is resource-intensive, i.e., the volume of the increasingly costly solid wood members required for construction of a wall is relatively large relative to the loads carried by the wood members.

These and other disadvantages are addressed by the insulated structural member of the present invention. In this engineered structural member, substantially less solid wood is needed, and insulating material may be added to provide resistance to heat transfer between the inner and outer surfaces of the wall into which the engineered structural member is incorporated.

In one embodiment of a 2x6 member, a conventional solid 2x4 is rip-cut along its longitudinal centerline, resulting in two narrower length wood flange sections. Each of these cut flanges are provided with a longitudinal slot in their 1.5″ wide faces, sized to receive a relatively rigid thin sheet of material. This “web” member in turn is sized such that when the slots in the flanges are located over the opposite edges of the thin sheet, the overall width of the composite structural member is 5.5″ wide, i.e., a “2x6” is generated. Preferably, the web material is formed from cost-stable web material with superior moisture resistance as compared to osb and plywood, and uses recycled material (for example, 94% post-consumer recycled content & fibers).

The present invention’s structural member accordingly uses substantially less solid wood, with commensurate reduction in the cost and weight of the engineered “2x6” (on the order of 40% less by volume and 60% less by weight in a 2x6 embodiment, depending on the moisture content of the wood), and reduces the demand for harvesting natural resources.

The thermal conductivity of the structural member in the 5.5″ direction is reduced by the insulating effect of the very small heat conduction cross-section of the thin sheet web between the slots. The insulation effect is enhanced by including foam insulation in the recesses between the opposing wood flanges on one or both sides of the web. The foam insulation reduces both radiant heat transfer from one wood flange to the other, and radiant and convective heat transfer to the engineered 2x6 structural member from the interior space between adjacent engineered 2x6 structural member of the wall. The foam also acts to prevent thermal bridging of fasteners used to secure exterior sheathing and cladding.

In addition to the cost and material reductions associated with the inventive engineered structural member itself, the present invention may reduce in-situ labor costs by presenting only a relatively thin and easily penetrated web for an installer to cut through when passing utility runs through the wall. This would be the case with both horizontal utility runs and vertical utility runs through headers and/or sill plates arranged with their web sections parallel to the floor.

The engineered structural member also has the advantage of being lighter, stronger and more dimensionally stable than solid lumber (i.e., less susceptible to twisting, warping and shrinking), despite having a smaller cross sectional area. This stability may help minimize “nail pops,” where nail heads are pushed out above the surface of a drywall sheet. In addition, the additional load capacity may enable design of lighter, less costly structures (for example, by allowing greater spacing of vertical members, or the use of smaller-dimensioned headers and/or footers). The present approach may also minimize the effect of “thermal bridging” through fasteners that occur with solid lumber use with exterior rigid foam and sheathing installations.

Depending on the overall insulation effectiveness of a structure built from the present invention’s engineered structural member, it may be possible to meet prescriptive energy code requirements for continuous insulation and fenestration values that are not achievable using solid wood framing members, and eliminate the need for expensive exterior rigid foam insulation and spray foam within the wall cavity.

The above example is merely representative. Other sizes of engineered structural members embodying the present invention, such as 2x8s, may be formed using appropriately sized flanges, webs and optionally inter-flange insulating material such as rigid foam or spray foam material. Further, the present invention is not limited to a single web member between flanges, but may include multiple webs and additional insulation between the webs. Moreover, the present invention is not limited to flanges and/or webs produced solely by cutting apart dimensional lumber or otherwise homogeneous wood, but may be produced from other materials such as plywood, osb, and/or engineered lumber.

The present invention’s engineered structural member has many applications, including use as sill plates, headers, cripples, jacks studs, splines, columns, etc., and may be used wherever equivalent-sized solid lumber is used. For example, appropriately arranged, the inventive structural member may be used to form a continuous insulated “thermal break” within a wall cavity. Those familiar with structure construction will recognize that there will be other applications in which the engineered structural member may be used to replace conventional lumber. For example, depending on the application, different sizes of engineered structural members may be used together, such as using 2x6 vertical studs with a nominal 4x6 header or sill plate where additional load capacity is desired. Different lengths may also be used, including lengths that are standard in the industry such as 8-foot, 9-foot and 10-foot lengths, as well as extended (e.g., 22-foot) or shorter lengths.

The present invention is not limited to being sized to correspond to nominal size lumber, but may be constructed to any desired width and depth combination which meets a desired application, such as a wall with a desired custom depth.

In another embodiment of the present invention, the web between the flanges may be non-continuous. For example, relatively short web sections may be spaced apart from one another along the length of the engineered structural member, thereby further reducing weight and material cost, with only a small, or even no, reduction in structural strength.

A further embodiment uses conventional nail plates, i.e., reinforcing metal plates that are installed alongside joints to increase the joint’s strength, in place of the web or web sections. As which the previous embodiment, insulation also may be added in the gaps between nail plates to increase the effectiveness of the thermal break.

In another embodiment of the present invention, multiple webs may be used to link multiple flanges, for example, to create an extended in-line structural panel or to create a structural member with flanges at an angle to one another to form a portion of, or a complete, column member. Examples, of which angled structural members include, but are not limited to, an “L″-shaped corner, a square column or a hexagonal column.

The present invention thus provides the wood framed construction industry a lighter, more dimensionally stable alternative to solid wood framed wall construction, while still being able to meet code-required continuous insulation values by providing a continuous insulated thermal break within a wall cavity. This engineered structural member further is compatible with any type of insulation within the wall cavity, and has insulation performance that permits avoiding the disadvantages associated with the use of spray foam insulation within a wall cavity.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show an engineered structural member in accordance with an embodiment of the present invention.

FIG. 2 shows dimensions of a wood block from which the flanges of FIGS. 1A and 1B may be produced in accordance with the present invention.

FIG. 3 shows a wall structure constructed with the engineered structural member of FIG. 1 .

FIG. 4 shows another embodiment of an engineered structural member in accordance with an embodiment of the present invention.

FIG. 5 shows another embodiment of an engineered structural member in accordance with an embodiment of the present invention.

FIGS. 6A and 6B show shows another embodiment of an engineered structural member in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

FIGS. 1A and 1B shows illustrations of a cross-section and perspective views, respectively, of an embodiment of the present invention referred to as Insul-Stud™. Both of these views show a nominal 2x6 stud having a width W of 5.5 inches and a depth D of 1.5 inches. The length L of the engineered structural member may be as needed, for example, a standard length of 8 feet, or a length to suit a particular application.

The assembled engineered structural member 10 includes flanges 11, 12, a web 13 engaged in slots 14, 15 in the flanges 11, 12, and insulation elements 16, 17 spanning the open spaces (“bays”) between the opposing faces of the flanges 11, 12 on the exposed faces 18, 19 of the web 13. At a nominal 2x6 lumber size, the engineered structural member uses approximately 40% less wood than a solid 2x6 piece of lumber of equivalent length. The engineered structural member may be used for vertical wall studs, headers and footers.

In this embodiment, the slots 14, 15 have a depth of 0.5 inches and a width of 0.125 inches. The web 13 has a width of 3.5 inches. The combination of the two 1.5 inch flanges 11, 12, the two 0.5 inch deep slots 14, 15, and the 3.5 inch web 13 result in an assembled structure with the nominal dimensions of a 2x6 (i.e., 1.5 inches by 3.5 inches) and a gap 2.5 inches wide between the flanges.

An efficient and cost-effective approach to producing the flanges 11, 12 in this embodiment is shown the cross-section view in FIG. 2 . A solid piece of 2x4 lumber 20 (having nominal dimensions of 1.5 inches by 3.5 inches) may be rip-cut along the center 21 of its 3.5″ dimension to create the two flanges 11, 12. In this embodiment the flanges are symmetrical, however non-symmetrical shapes may be generated as long as the final assembled engineered structural member is dimensioned as needed by the intended application.

If the kerf 22 of the saw blade cut is 0.125 inches width, the resulting dimensions of the flanges 11, 12 are 1.5 inches wide by 1.6875 inches deep ((3.5″-0.125″)/2). Also shown in FIG. 2 are the 0.5 inch deep, 0.125 inch wide slots 14, 15 cut into the flanges 11, 12 to accommodate the opposite edges of the web 13. In this embodiment the slots 14, 15 are cut at the center of the respective 1.6875 inch deep flange sides, but they may be placed off-center in these flange sides to produce asymmetric spaces between the flanges. The slots 14, 15 may alternatively be cut into the base 2x4 lumber before, or simultaneously with, the cutting of the 2x4 into the two flanges 11, 12.

Preferably, during assembly of the engineered structural member an adhesive, preferably waterproof, is placed into the slots 14, 15 and/or onto the opposing edges of the web 13 before or during the insertion of the web 13 into the slots. The assembled structural member may be clamped during curing of the adhesive to ensure consistent dimensions of the assembled member (i.e., avoiding one flange being slightly rotated about its longitudinal axis relative to the other flange), or alternatively may be left to cure without support if the resulting product is dimensionally suitable for the intended application. Optionally, heat may be used to enhance the adhesive curing process. Once cured, the engineered structural member is ready for any necessary precision dimensioning such as length trimming, then packaging and shipment. Alternatively or in addition, the web may be secured in the slots by mechanical fasteners such as nails, staples, screws, etc.

The materials of the inventive engineered structural member may include, for the flanges, specially-source lumber of suitable species and/or grade for the intended application. For example, visually graded douglas fir larch #2 may be desirable for cost, cutting ease and/or load capacity reasons.

The web member is preferably a thin sheet material with minimal weight but sufficient rigidity to support the opposing flanges at least until the engineered structural member is incorporated into a structure such as a wall. For example, lightweight, extrusion-coated cellulosic fiber boards may provide high strength, durability and superior moisture resistance compared to plywood where the strength characteristics of plywood are not needed, while being composed of fibers with ecologically-friendly post-consumer recycled content (e.g., 94% recycled content).

In embodiments in which additional insulation is to be located between the flanges at the exposed sides of the web, a preferred insulation material is ¾″x2-½″ XPS rigid foam, having an insulating value of 12.5. Other forms of lightweight insulating material may be used without departing from the present invention. Preferably the insulating material is adhered to the web and/or flanges with a waterproof adhesive, so that the insulation remains in place during handling and subsequent in-place service.

The adhesive used to bond the flanges and web together preferably is a liquid phenol-resorcinol resin adhesive, which is a two-part system which provides a waterproof, strong structural bond. For example, Aerodux 185® with HRP 155® hardener, when fully cured, is resistant to acids, weak alkalis, solvents and boiling water. Aerodux 185® is also suitable for bonding a wide range of materials to porous substrates, including wood (including improved or densified woods), mineral fiber reinforced boards, brick, concrete, unglazed porcelain, rigid expanded plastics (e.g., expanded polystyrene, polyurethane, PVC), industrial and decorative laminates (phenolic resin-based or phenolic resin backed), leather, cork, linoleum and nylon.

FIG. 3 illustrates an embodiment of a wall structure constructed with the engineered structural member described above. This wall structure may be built in-situ, or may be provided as preassembled modular panels to increase worksite construction efficiency. In this wall structure 30 four vertical Insul-Stud™ members 31-34 are arranged on an Insul-Stud™ footer 35 and linked at their upper ends by a double-header 36 formed from two Insul-Stud™ engineered structural members 37, 38. In addition to the insulation in the bays of the Insul-Studs™, in this wall embodiment the space between the vertical Insul-Stud™ members 31-34 are filled with additional insulation material, here a compression-fit R19 kraft-faced batt fiberglass insulation, with the kraft faces being arranged toward a covering drywall sheet 39. If the wall structure is a preassembled panel, the drywall sheet may be affixed to the Insul-Stud™ members by any suitable technique, such as by the use of staples such as Senco® P19AB staples. Optionally, an opposite covering panel such as an oriented stranded board (“OSB”) sheathing may be similarly stapled or otherwise adhered to the wall structure 30. Also optionally, an air sealing caulk my be applied in a continuous bead at the double-header 36 to block air infiltration.

FIG. 4 shows a schematic illustration of an engineered structural member 40 in which the web between the opposing flanges 41, 42 is not continuous, but instead includes multiple short sections of webs 43 which engage the flanges’ slots in a spaced-apart arrangement. The web sections may be formed from the fiber-based materials discussed above, or from metal or a plastic material which provides sufficient structural rigidity to the member. This embodiment the web sections 43 are standard 4x3 nail plates. Insulation material 44 is arranged between the web sections 43 to enhance the thermal break effect.

The FIG. 4 engineered structural member 40 has the nominal dimensions of a 2x6 by 8-foot piece of lumber, having a 1.5 inch depth (into the plane of the page), a 5.5 inch width W, and the web sections 43 at a 31 inch center-to center spacing S.

Alternatively, FIG. 5 shows an embodiment of a 2x6 engineered structural member 50 in which 4 inch x 3 inch nail plates 53 are affixed to the sides of the flanges 51, 52. The flanges 51, 52 in this embodiment are conventional 2x2 lumber, having depth and width dimensions of 1.5 inches by 1.5 inches. With the ends of the nail plates centered over the centers of the flanges 51, 52, a nominal 6 inch width W (4 + 0.75 + 0.75 = 5.5 inches) structure is formed. Within the 3.5 inch space between the flanges 51, 52 created by the 4 inch length L1 of the nail plate 53, insulation material such as 1.5 inch thick XPS foam may be installed to enhance the effectiveness of the thermal break structure. Due to the relatively thin dimension of the nail plates, the nominal 1.5-inch depth D of the nominal 2 inch dimension of the 2x6 remains substantially unchanged. This embodiment is particularly well-suited to applications in which the structural members will not be in contact with one another across their width faces, so that the thickness of the nail plates is of no consequence to the overall structure.

FIGS. 6A and 6B show embodiments of the present invention composed of more than two flange members. FIG. 6A shows an engineered structural panel 60 having three flange members 61, 62. The two flange members 61 each have a single slot 64 to receive a web 63, and the third flange member 62 has two slots on opposite faces. The webs 63 are aligned parallel to one another. In FIG. 6B, the third flange member 63 has its two slots at adjacent faces, resulting in this embodiment having a 90° column structure. Alternatively, the slots in the third flange member 62 may be arranged such that the webs members 64 are arranged at any angle between 0°-180°. The present invention is not limited to three flange members, but may include multiple flange members and corresponding webs which extend the engineered structural member to a desired extent, either linearly or in a curved extent, up to and including a closed structure in the form of a light-weight, hollow column.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Because such modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

Listing of reference labels 10 engineered structural member 11, 12 flanges 13 web 14, 15 slots 16, 17 insulation 18, 19 web faces 20 lumber 21 center 22 saw blade kerf 30 wall structure 31-34 engineered structural members 35 footer, aka sill plate 36 double-header 37, 38 engineered structural members 39 drywall sheet 40 engineered structural member 41, 42 flanges 43 web sections 44 insulation 50 engineered structural member 51, 52 flanges 53 web sections 54 insulation 61, 62 flanges 62 webs 64 slots D depth W width L length L1 nail plate length S spacing 

What is claimed is:
 1. A structural member, comprising: two flange members; a web member; and an insulation material, wherein each of the two flange members has a slot, each of the slots has a width corresponding to a thickness of the web member, the web member engages each of the slots in the two flange members such that the two flange members are separated by the web member and a space between the two flange members contains the insulation material.
 2. A structural member, comprising: two flange members; and at least one web member, wherein each of the two flange members has at least one longitudinal slot arranged at a first face, each of the at least one longitudinal slot has a width corresponding to a thickness of the at least one web member, the at least one web member engages a corresponding one of the at least one longitudinal slots of each of the two flange members such that the first faces of the two flange members are facing one another.
 3. The structural member of claim 2, wherein the two flange members are separate by the at least one web member at a predetermined spacing determined by a width of the at least one web member.
 4. The structural member of claim 3, wherein the at least one web is secured by one or more of an adhesive and a mechanical fastener in a corresponding one of the at least one longitudinal slots of each of the two flange members.
 5. The structural member of claim 3, further comprising: an insulation material located in a space between the first faces of the two flange members.
 6. The structural member of claim 5, wherein a width of the at least one web member in a direction between the two flange members and a depth of each of the at least one longitudinal slots are sized such that the structural member has a size corresponding to an industry-standard nominal lumber size.
 7. The structural member of claim 5, wherein the at least one web member includes a plurality of web members spaced apart along a longitudinal direction of the structural member.
 8. The structural member of claim 5, wherein the at least one longitudinal slot is a plurality of longitudinal slots in the first face of each of the two flange members, the at least one web member includes a plurality of web members spaced apart from one another in a direction perpendicular to a direction between the two flange members, and each of the plurality of web members engages corresponding ones of the plurality of longitudinal slots opposing one another at the first faces of the two flange members.
 9. A structural member, comprising: three flange members; two web members; and an insulation material, wherein a first flange member of the three flange members has a first slot, a second flange member of the three flange members has a second slot, a third flange member of the three flange members has a third slot on a first face and a fourth slot on a second face, each of the slots has a width corresponding to a thickness of the web members, a first one of the two web members engages the first slot of the first flange member and the third slot of the third flange member such that the first and third flange members are separated by the first web member, and a second one of the two web members engages the second slot of the second flange member and the fourth slot of third flange member such that the second and third flange members are separated by the second web member.
 10. The structural member of claim 9, further comprising: an insulation material located in one of both of a first space between the first and third two flange members and a second space between the second and third flange members.
 11. The structural member of claim 10, wherein the first and second web members are arranged parallel to one another.
 12. The structural member of claim 10, wherein the first and second web members are arranged at an angle to one another.
 13. The structural member of claim 12, wherein the first and second web members are arranged at a 90° angle to one another.
 14. A method of production of a structural member, comprising the steps of: providing two flange members and a web member, each flange member having at least one longitudinal slot on at least one face; inserting a first edge of the web member into the at least one longitudinal slot of a first flange member of the two flange members; inserting a second edge of the web member at a side of the web member opposite the first edge into the at least one longitudinal slot of a second flange member of the two flange members; and inserting an insulation material into a space between the two flange members adjacent to the at least one web member, wherein each of the at least one longitudinal slots has a width corresponding to a thickness of the at least one web member.
 15. The method of production of a structural member of claim 14, further comprising the step of: securing the first and second edges of the web member in the respective first and second flange members with one or both of an adhesive and mechanical fasteners.
 16. The method of production of a structural member of claim 14, further comprising the step of: forming the two flange members by dividing lumber having an industry-standard nominal lumber size.
 17. The method of production of a structural member of claim 14, wherein the two flange members are lumber having an industry-standard nominal lumber size. 